#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int main() {
	FILE* pf = fopen("test.txt", "w");
	if (pf == NULL) {
		perror("fopen");
	}
	fputs("hello world\n", pf); 
	fputs("hello world", pf);

	fclose(pf);
	pf = NULL;

	return 0;
}